A liquid crystal panel, particularly a liquid crystal panel of the TN systems and the STN systems has a structure in which a black matrix is provided on a glass substrate for emphasizing the contrast of images, on which a transparent protective film, a transparent electrode, an orientation film, liquid crystals, a transparent electrode, a transparent protective film, a back light and the like are sequentially laminated, and sealing portions for maintaining the air tightness of the edges of said members. In color liquid crystal panel, color filters are also provided. In order that such a liquid crystal display panel maintains the contrast of images high, the light shielding capacity of the black matrix must be an optical density value (hereafter simply referred to as OD value) of 1.5 or more. Moreover, due to the problems of color filters and planarizing of transparent protective films, the black matrix must be as thin as possible. The black matrix is produced by photolithography after dissolving a photosensitive resin composition for forming a light shielding film containing a light shielding pigment and a photosensitive resin in a solvent, coating the solution on the surface of a liquid crystal panel substrate, and drying the coating. It is essential for obtaining a black matrix of a high OD value, that a highly light-shielding pigment is used, and carbon black having a high light shielding capacity is normally used.
In a simple matrix liquid crystal display panel such as that of the STN system having conventional black matrix described above, or a TFT-on-array display, voltage between transparent electrodes holding liquid crystals must be constant to keep images displayed even. However, since carbon black is conductive and electric current leaks from the transparent electrodes to the black matrix, the voltage is difficult to be constant, and time for operation using a battery cannot be increased. In addition, from the structural nature of the liquid crystal display panel, electric current easily leaks from the sealing portion of the panel, which makes more difficult to make the voltage constant. In order to solve such problems, photosensitive resin compositions for forming shielding films containing inorganic pigments such as titanium black, or organic pigments such as perylene black have been proposed, but it has been difficult to achieve high OD values, and black matrix layers must be thickened for obtaining high contrast. This results in disadvantages in that the planarization of color filters and transparent protective films is difficult, and images displayed become uneven.
In these situations, we, the present inventors have assiduously studied so as to develope a photosensitive resin composition for forming light shielding films and, as a result, have found that the above problems were solved by incorporating carbon black coated with resin in the photosensitive resin composition for forming light shielding films. On the basis of these findings, we have completed the present invention.